1. Field of the Invention
The present invention relates to an electromagnetic field measurement system for measuring an electromagnetic field by means of an electromagnetic field probe, and to a radiated immunity system.
The present invention also relates to an electromagnetic field probe used for measuring an electromagnetic field, and to a radio wave absorber and an exterior body that cover an electromagnetic field probe for measuring an electromagnetic field.
2. Description of the Related Art
Many electromagnetic wave sources, such as electronic equipment, electrical appliances, and radio equipment, have recently become prevalent in home. Electromagnetic waves originating from the electromagnetic wave sources have the potential risk of affecting the ambient electromagnetic-wave environment in various manners, and the electronic equipment, or the like, which becomes the source of electromagnetic waves may also be affected by the electromagnetic environment originating from another electromagnetic wave source. For these reasons, the electronic equipment is desired to prevent emission of electromagnetic waves outside the equipment and to have EMC (Electro-Magnetic Compatibility) measures of resistance to the ambient electromagnetic environment.
The EMC measures must be adopted so as to address emission or EMI (Electro-Magnetic Interface) and immunity or EMS (Electro-Magnetic Susceptibility).
IEC61000-4-3 is available as upstandards for evaluating immunity of such electronic equipment or the like. In order to evaluate resistance of electronic equipment to electromagnetic interference, a test defined by the regulations is conducted by exposing a device under test or EUT (Equipment under Test) to electromagnetic interference to which electronic equipment is presumed to be exposed, and observing the behavior of the device or EUT.
A specific configuration for an immunity test is described in JP-A-4-029069. The document JP-A-4-029069 describes the steps of: emitting electromagnetic wave noise toward a device under test placed in a radio wave shielded chamber whose wall surfaces are filled with radio absorbers; and a technician monitoring whether or not the device under test performs faulty operation when exposed to this disturbance factor, by way of a monitor. Evaluation of immunity of such electronic equipment to radiation noise entails prevention of influence of electromagnetic wave noise to the outside and highly accurate measurement of a characteristic.
In order to conduct an immunity test, formation of a uniform electric field region within the radio wave shielded chamber must have been ascertained in advance. Ascertaining the performance of such a radio wave shielded chamber requires measuring the value of electric field intensity in the radio wave shielded chamber through use of a field sensor; and recording the resultant deviation.
As to a field sensor, a product capable of measuring a broadband frequency exceeding 1 GHz is commercially available (e.g., a probe manufactured by ETSLINDGREN Co., Ltd.), and the value of field intensity in the radio wave shielded chamber is measured by use of the field sensor.